Stockton Mine on the West Coast of the South Island was the home of Doug Hood Mining Ltd for 7½ years.
Saturday 31st July 2010 saw the completion of a plant hire arrangement between Doug Hood Mining and the Stockton Alliance, and the conclusion of a significant programme of opencast mining and civil engineering work for Solid Energy NZ Ltd at Stockton Mine.
We continue to seek opportunities to utilise our comprehensive plant fleet and management experience in mining and civil engineering projects throughout New Zealand.
Doug Hood Mining had already established a history of completed projects at Stockton Mine, New Zealand’s largest mine, including a contract for overburden removal and coal mining from 1985 to 1989, the Mt Augustus haul-road construction from 2002 to 2003, and the Mt Frederick drainage & side cast from 2003 to 2005.
In November 2003 Doug Hood Mining tendered for and won the 5 year contract, which was extended to October 2009, for overburden removal, coal winning and associated work as the principal mining contractor.
Mining was on a 24/7 operational basis, utilising up to 3 x 180 tonne excavators as the main digging tools. Coal was predominantly mined with 2 x 100 tonne excavators. A fleet of up to 29 x 85-100 tonne 777’s, 4 x 50 tonne 773’s and 24 x 35-40 tonne articulating dump trucks, were used for both coal and overburden mining. D8, D9 & D11 tractors were utilised in pits and on tip heads. Fleet size at the end of the Stockton contract was 128 items of heavy plant.
Overburden stripping and coal winning were from multiple pits on an ongoing basis. Mining included extensive previous (historic) underground workings. Overburden consisted mainly of competent granites and some mudstones. Site mobility was greatly reduced by the impact of water on haul roads and pit access due to the site receiving up to 7 metres of rain per annum.
Overburden removal increased 100% from tender to up to 500,000 m3 per month with 24.5 million m3 moved on contract over the 6 year contract period. The tendered plant fleet increased four fold to achieve these production increases.
Stockton coal varies in quality and seam thickness and is selectively mined accordingly hence coal winning was characterised by complex blending of multiple coal face & stockpile sources, with up to 10 or more mixed on a shift.
With coal winning requiring a minimum of 8,000 tonne of coal per 24 hours, approximately 9.1 million tonnes of coal was handled to ROM or stockpile with a peak production of 2.1 million tonnes per annum.
Rehabilitation and auxiliary works
Rehabilitation and auxiliary civil works such as drainage, piping, catchment sumps, pumping and haul road construction and maintenance were undertaken on a continuous basis utilising the large fleet of smaller excavators, articulated dump trucks and specialist crews.
Difficult stripping of previous workings provided challenges to drill & blast, overburden removal and coal winning, while severe weather (including fog-outs) was often a challenging factor for all site activities.
Total employees associated with this contract increased from 100 at contract commencement to a peak of 450 employees.
In 2007 Doug Hood Mining tendered for and won the contract to construct the Mangatini Sump within the Stockton Mine site, and completed this in 2009. The sump required the drill, blast, excavation and dumping of 1.6M m3 of solid rock, and is a key component of the Stockton water management programme.
End of contract
The Stockton Mine contract ended on 2nd October 2009, however 100 heavy plant items remained in operation on hire until 31st July 2010.